struct.unpack doens't support buffer protocol objects

[moese]

BPO	1563759
Nosy	@loewis, @rhettinger
Files	test_struct.py: Append to end of test_struct.py test_struct_run.py: Runnable test version for both Python 2.4 and 2.5

^{Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.}

Show more details

GitHub fields:

assignee = None
closed_at = <Date 2007-04-04.20:32:41.000>
created_at = <Date 2006-09-22.22:17:45.000>
labels = ['library']
title = "struct.unpack doens't support buffer protocol objects"
updated_at = <Date 2007-04-04.20:32:41.000>
user = 'https://bugs.python.org/moese'

bugs.python.org fields:

activity = <Date 2007-04-04.20:32:41.000>
actor = 'rhettinger'
assignee = 'none'
closed = True
closed_date = None
closer = None
components = ['Library (Lib)']
creation = <Date 2006-09-22.22:17:45.000>
creator = 'moese'
dependencies = []
files = ['2149', '2150']
hgrepos = []
issue_num = 1563759
keywords = []
message_count = 8.0
messages = ['29930', '29931', '29932', '29933', '29934', '29935', '29936', '29937']
nosy_count = 3.0
nosy_names = ['loewis', 'rhettinger', 'moese']
pr_nums = []
priority = 'high'
resolution = 'fixed'
stage = None
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue1563759'
versions = ['Python 2.5']

[moese]

If you pass an object which supports the buffer
protocol to struct.unpack it will fail because it
specifically checks for a string.

You should use PyObject_AsReadBuffer instead.

If this code is performance critical, you could add an
unpack_buffer method or something like that.

[loewis]

Logged In: YES
user_id=21627

Why is this a bug?

[moese]

Logged In: YES
user_id=1067739

Well, because it broke previously working code and there is
no warning in the documentation about that.

In the mean-time, I've found out about pack_into and
unpack_from which accept buffer like objects. Note that they
are not documented in the struct module section, only
mentioned in the "What's new" chapter.

[loewis]

Logged In: YES
user_id=21627

Ah, so you say that was working previously? It's a bug,
then. Can you provide a test case?

[moese]

Logged In: YES
user_id=1067739

The actual code which broke used a Pointer extension class
implemented in C++.

I reproduced the problem using array.array. Using array in
this way (without calling tostring) looks a bit weird.

[moese]

Logged In: YES
user_id=1067739

test_struct_run.py works in 2.4, throws exception in 2.5

[rhettinger]

This was due to Bob Ippolito's commit in revision 46184.

[rhettinger]

Fixed. See revision 54690.